When using the /enchant command on an item already enchanted with the enchantment already applied, the error is incorrect. For example, if I have a `diamond_sword` with `minecraft:sharpness 2` and I would like to enchant this sword to level 5, with the command `/enchant @s minecraft:sharpness 5`, the error is incorrect. It shows "Diamond sword can't have that enchantment" when in fact, it can.

There are two ideal solutions to this problem.
1. Change the functionality of /enchant to allow re-enchanting an item already enchanted with the desired enchantment. (Best case)

2. Change the error to state "You may not enchant an item with an enchantment it already has" or something similar.